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World J Orthop. Jul 18, 2013; 4(3): 112-113
Published online Jul 18, 2013. doi: 10.5312/wjo.v4.i3.112
Cervical adjacent segment pathology following fusion: Is it due to fusion?
Philip Rosenthal, Kee D Kim
Philip Rosenthal, Kee D Kim, Department of Neurological Surgery, UC Davis Health System, Sacramento, CA 95817, United States
Author contributions: Rosenthal P and Kim KD contributed to the writing and editing of the piece; Kim KD contributed the theory of the editorial.
Correspondence to: Kee D Kim, MD, Associate Professor, Chief of Spinal Neurosurgery, Department of Neurological Surgery, UC Davis Health System, 3860 Y Street, Suite 3740, Sacramento, CA 95817, United States. Kee.kim@ucdmc.ucdavis.edu
Telephone: +1-916-7347463 Fax: +1-916-7035368
Received: March 7, 2013
Revised: May 2, 2013
Accepted: May 18, 2013
Published online: July 18, 2013

Adjacent segment pathology affects 25% of patients within ten years of anterior cervical diskectomy and fusion (ACDF). Laboratory studies demonstrate fused segments increase adjacent level stress including elevated intradiscal pressure and increased range of motion. Radiographic adjacent segment pathology (RASP) has been associated to ACDF in multiple statistically significant studies. Randomized controlled trials (RCTs) comparing anterior cervical discectomy and arthroplasty (ACDA) and ACDF have confirmed ACDF accelerates RASP. The question of greatest clinical interest is whether ACDA, artificial disc surgery, results in fewer adjacent level surgeries than ACDF. Current RCT follow up results reveal only non statistically significant trends favoring ACDA yet the post operative periods are only two to four years. Statistically significant increased RASP in ACDF patients however is already documented. The RCT patients’ average ages are in the mid forties with an expected longevity of up to forty more years. Early statistically significant increased RASP in the ACDF patients supports our prediction that given sufficient follow up of ten or more years, fusion will lead to statistically significant higher rate of adjacent level surgery compared to artificial disc surgery.

Keywords: Cervical, Diskectomy, Fusion, Arthroplasty, Adjacent, Degeneration

Core tip: Cervical artificial disc surgery has brought the expectation of a lower rate of adjacent segment pathology. Randomized controlled trials (RCTs), currently have only two to four years follow ups and the results regarding adjacent segment surgery indicate only non statistically significant trends favoring the anterior cervical discectomy and arthroplasty (ACDA). Higher rates of radiographic adjacent level pathology, after anterior cervical diskectomy and fusion (ACDF) is already documented. We predict that as the RCT average age mid forty-year-old patients continue to their almost forty year expected longevity, adjacent level surgery rates after ACDF will also increase in comparison to the ACDA patients.